/*
 * lm75.c - Part of lm_sensors, Linux kernel modules for hardware
 *       monitoring
 * Copyright (c) 1998, 1999  Frodo Looijaard <frodol@dds.nl>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include "lm75.h"


/*
 * This driver handles the LM75 and compatible digital temperature sensors.
 */

enum lm75_type {                /* keep sorted in alphabetical order */
        adt75,
        ds1775,
        ds75,
        lm75,
        lm75a,
        max6625,
        max6626,
        mcp980x,
        stds75,
        tcn75,
        tmp100,
        tmp101,
        tmp105,
        tmp175,
        tmp275,
        tmp75,
};

/* Addresses scanned */
static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
                                        0x4d, 0x4e, 0x4f, I2C_CLIENT_END };


/* The LM75 registers */
#define LM75_REG_CONF           0x01
static const u8 LM75_REG_TEMP[3] = {
        0x00,           /* input */
        0x03,           /* max */
        0x02,           /* hyst */
};

/* Each client has this additional data */
struct lm75_data {
        struct device           *hwmon_dev;
        struct mutex            update_lock;
        u8                      orig_conf;
        char                    valid;          /* !=0 if registers are valid */
        unsigned long           last_updated;   /* In jiffies */
        u16                     temp[3];        /* Register values,
                                                   0 = input
                                                   1 = max
                                                   2 = hyst */
};

static int lm75_read_value(struct i2c_client *client, u8 reg);
static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
static struct lm75_data *lm75_update_device(struct device *dev);


/*-----------------------------------------------------------------------*/

/* sysfs attributes for hwmon */

static ssize_t show_temp(struct device *dev, struct device_attribute *da,
                         char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        struct lm75_data *data = lm75_update_device(dev);

        if (IS_ERR(data))
                return PTR_ERR(data);

        return sprintf(buf, "%d\n",
                       LM75_TEMP_FROM_REG(data->temp[attr->index]));
}

static ssize_t set_temp(struct device *dev, struct device_attribute *da,
                        const char *buf, size_t count)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
        struct i2c_client *client = to_i2c_client(dev);
        struct lm75_data *data = i2c_get_clientdata(client);
        int nr = attr->index;
        long temp;
        int error;

        error = kstrtol(buf, 10, &temp);
        if (error)
                return error;

        mutex_lock(&data->update_lock);
        data->temp[nr] = LM75_TEMP_TO_REG(temp);
        lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
        mutex_unlock(&data->update_lock);
        return count;
}

static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
                        show_temp, set_temp, 1);
static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
                        show_temp, set_temp, 2);
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);

static struct attribute *lm75_attributes[] = {
        &sensor_dev_attr_temp1_input.dev_attr.attr,
        &sensor_dev_attr_temp1_max.dev_attr.attr,
        &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,

        NULL
};

static const struct attribute_group lm75_group = {
        .attrs = lm75_attributes,
};

/*-----------------------------------------------------------------------*/

/* device probe and removal */

static int
lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
        struct lm75_data *data;
        int status;
        u8 set_mask, clr_mask;
        int new;

        if (!i2c_check_functionality(client->adapter,
                        I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
                return -EIO;

        data = kzalloc(sizeof(struct lm75_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        i2c_set_clientdata(client, data);
        mutex_init(&data->update_lock);

        /* Set to LM75 resolution (9 bits, 1/2 degree C) and range.
         * Then tweak to be more precise when appropriate.
         */
        set_mask = 0;
        clr_mask = (1 << 0)                     /* continuous conversions */
                | (1 << 6) | (1 << 5);          /* 9-bit mode */

        /* configure as specified */
        status = lm75_read_value(client, LM75_REG_CONF);
        if (status < 0) {
                dev_dbg(&client->dev, "Can't read config? %d\n", status);
                goto exit_free;
        }
        data->orig_conf = status;
        new = status & ~clr_mask;
        new |= set_mask;
        if (status != new)
                lm75_write_value(client, LM75_REG_CONF, new);
        dev_dbg(&client->dev, "Config %02x\n", new);

        /* Register sysfs hooks */
        status = sysfs_create_group(&client->dev.kobj, &lm75_group);
        if (status)
                goto exit_free;

        data->hwmon_dev = hwmon_device_register(&client->dev);
        if (IS_ERR(data->hwmon_dev)) {
                status = PTR_ERR(data->hwmon_dev);
                goto exit_remove;
        }

        dev_info(&client->dev, "%s: sensor '%s'\n",
                 dev_name(data->hwmon_dev), client->name);

        return 0;

exit_remove:
        sysfs_remove_group(&client->dev.kobj, &lm75_group);
exit_free:
        kfree(data);
        return status;
}

static int lm75_remove(struct i2c_client *client)
{
        struct lm75_data *data = i2c_get_clientdata(client);

        hwmon_device_unregister(data->hwmon_dev);
        sysfs_remove_group(&client->dev.kobj, &lm75_group);
        lm75_write_value(client, LM75_REG_CONF, data->orig_conf);
        kfree(data);
        return 0;
}

static const struct i2c_device_id lm75_ids[] = {
        { "adt75", adt75, },
        { "ds1775", ds1775, },
        { "ds75", ds75, },
        { "lm75", lm75, },
        { "lm75a", lm75a, },
        { "max6625", max6625, },
        { "max6626", max6626, },
        { "mcp980x", mcp980x, },
        { "stds75", stds75, },
        { "tcn75", tcn75, },
        { "tmp100", tmp100, },
        { "tmp101", tmp101, },
        { "tmp105", tmp105, },
        { "tmp175", tmp175, },
        { "tmp275", tmp275, },
        { "tmp75", tmp75, },
        { /* LIST END */ }
};
MODULE_DEVICE_TABLE(i2c, lm75_ids);

#define LM75A_ID 0xA1

/* Return 0 if detection is successful, -ENODEV otherwise */
static int lm75_detect(struct i2c_client *new_client,
                       struct i2c_board_info *info)
{
        struct i2c_adapter *adapter = new_client->adapter;
        int i;
        int conf, hyst, os;
        bool is_lm75a = 0;

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
                                     I2C_FUNC_SMBUS_WORD_DATA))
                return -ENODEV;

        /*
         * Now, we do the remaining detection. There is no identification-
         * dedicated register so we have to rely on several tricks:
         * unused bits, registers cycling over 8-address boundaries,
         * addresses 0x04-0x07 returning the last read value.
         * The cycling+unused addresses combination is not tested,
         * since it would significantly slow the detection down and would
         * hardly add any value.
         *
         * The National Semiconductor LM75A is different than earlier
         * LM75s.  It has an ID byte of 0xaX (where X is the chip
         * revision, with 1 being the only revision in existence) in
         * register 7, and unused registers return 0xff rather than the
         * last read value.
         *
         * Note that this function only detects the original National
         * Semiconductor LM75 and the LM75A. Clones from other vendors
         * aren't detected, on purpose, because they are typically never
         * found on PC hardware. They are found on embedded designs where
         * they can be instantiated explicitly so detection is not needed.
         * The absence of identification registers on all these clones
         * would make their exhaustive detection very difficult and weak,
         * and odds are that the driver would bind to unsupported devices.
         */

        /* Unused bits */
        conf = i2c_smbus_read_byte_data(new_client, 1);
        if (conf & 0xe0)
                return -ENODEV;

        /* First check for LM75A */
        if (i2c_smbus_read_byte_data(new_client, 7) == LM75A_ID) {
                /* LM75A returns 0xff on unused registers so
                   just to be sure we check for that too. */
                if (i2c_smbus_read_byte_data(new_client, 4) != 0xff
                 || i2c_smbus_read_byte_data(new_client, 5) != 0xff
                 || i2c_smbus_read_byte_data(new_client, 6) != 0xff)
                        return -ENODEV;
                is_lm75a = 1;
                hyst = i2c_smbus_read_byte_data(new_client, 2);
                os = i2c_smbus_read_byte_data(new_client, 3);
        } else { /* Traditional style LM75 detection */
                /* Unused addresses */
                hyst = i2c_smbus_read_byte_data(new_client, 2);
                if (i2c_smbus_read_byte_data(new_client, 4) != hyst
                 || i2c_smbus_read_byte_data(new_client, 5) != hyst
                 || i2c_smbus_read_byte_data(new_client, 6) != hyst
                 || i2c_smbus_read_byte_data(new_client, 7) != hyst)
                        return -ENODEV;
                os = i2c_smbus_read_byte_data(new_client, 3);
                if (i2c_smbus_read_byte_data(new_client, 4) != os
                 || i2c_smbus_read_byte_data(new_client, 5) != os
                 || i2c_smbus_read_byte_data(new_client, 6) != os
                 || i2c_smbus_read_byte_data(new_client, 7) != os)
                        return -ENODEV;
        }

        /* Addresses cycling */
        for (i = 8; i <= 248; i += 40) {
                if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
                 || i2c_smbus_read_byte_data(new_client, i + 2) != hyst
                 || i2c_smbus_read_byte_data(new_client, i + 3) != os)
                        return -ENODEV;
                if (is_lm75a && i2c_smbus_read_byte_data(new_client, i + 7)
                                != LM75A_ID)
                        return -ENODEV;
        }

        strlcpy(info->type, is_lm75a ? "lm75a" : "lm75", I2C_NAME_SIZE);

        return 0;
}

#ifdef CONFIG_PM
static int lm75_suspend(struct device *dev)
{
        int status;
        struct i2c_client *client = to_i2c_client(dev);
        status = lm75_read_value(client, LM75_REG_CONF);
        if (status < 0) {
                dev_dbg(&client->dev, "Can't read config? %d\n", status);
                return status;
        }
        status = status | LM75_SHUTDOWN;
        lm75_write_value(client, LM75_REG_CONF, status);
        return 0;
}

static int lm75_resume(struct device *dev)
{
        int status;
        struct i2c_client *client = to_i2c_client(dev);
        status = lm75_read_value(client, LM75_REG_CONF);
        if (status < 0) {
                dev_dbg(&client->dev, "Can't read config? %d\n", status);
                return status;
        }
        status = status & ~LM75_SHUTDOWN;
        lm75_write_value(client, LM75_REG_CONF, status);
        return 0;
}

static const struct dev_pm_ops lm75_dev_pm_ops = {
        .suspend        = lm75_suspend,
        .resume         = lm75_resume,
};
#define LM75_DEV_PM_OPS (&lm75_dev_pm_ops)
#else
#define LM75_DEV_PM_OPS NULL
#endif /* CONFIG_PM */

static struct i2c_driver lm75_driver = {
        .class          = I2C_CLASS_HWMON,
        .driver = {
                .name   = "lm75",
                .pm     = LM75_DEV_PM_OPS,
        },
        .probe          = lm75_probe,
        .remove         = lm75_remove,
        .id_table       = lm75_ids,
        .detect         = lm75_detect,
        .address_list   = normal_i2c,
};

/*-----------------------------------------------------------------------*/

/* register access */

/*
 * All registers are word-sized, except for the configuration register.
 * LM75 uses a high-byte first convention, which is exactly opposite to
 * the SMBus standard.
 */
static int lm75_read_value(struct i2c_client *client, u8 reg)
{
        if (reg == LM75_REG_CONF)
                return i2c_smbus_read_byte_data(client, reg);
        else
                return i2c_smbus_read_word_swapped(client, reg);
}

static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
{
        if (reg == LM75_REG_CONF)
                return i2c_smbus_write_byte_data(client, reg, value);
        else
                return i2c_smbus_write_word_swapped(client, reg, value);
}

static struct lm75_data *lm75_update_device(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct lm75_data *data = i2c_get_clientdata(client);
        struct lm75_data *ret = data;

        mutex_lock(&data->update_lock);

        if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
            || !data->valid) {
                int i;
                dev_dbg(&client->dev, "Starting lm75 update\n");

                for (i = 0; i < ARRAY_SIZE(data->temp); i++) {
                        int status;

                        status = lm75_read_value(client, LM75_REG_TEMP[i]);
                        if (unlikely(status < 0)) {
                                dev_dbg(dev,
                                        "LM75: Failed to read value: reg %d, error %d\n",
                                        LM75_REG_TEMP[i], status);
                                ret = ERR_PTR(status);
                                data->valid = 0;
                                goto abort;
                        }
                        data->temp[i] = status;
                }
                data->last_updated = jiffies;
                data->valid = 1;
        }

abort:
        mutex_unlock(&data->update_lock);
        return ret;
}

/*-----------------------------------------------------------------------*/

/* module glue */

static int __init sensors_lm75_init(void)
{
        return i2c_add_driver(&lm75_driver);
}

static void __exit sensors_lm75_exit(void)
{
        i2c_del_driver(&lm75_driver);
}

MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
MODULE_DESCRIPTION("LM75 driver");
MODULE_LICENSE("GPL");

module_init(sensors_lm75_init);
module_exit(sensors_lm75_exit);